My application for Rakuten NISA was rejected due to their security screening. Has anyone else experienced this? How did you resolve it?

My Rakuten NISA application was rejected after their security screening, and I can’t figure out why. I’m a PR holder and have lived in Japan for several years, so I don’t think residency should be an issue. During the application process their system had trouble with my long name, and we went back and forth a few times to correct it, so I thought it was resolved. Today I got a rejection with no explanation. Has anyone had a similar experience or found a solution?